Flexible display device and method for fabricating the same

ABSTRACT

A flexible display device includes a flexible substrate includes first and second portions that overlap each other, and a bending portion connecting the first portion with the second portion. A first display having a first organic light emitting diode is on the first portion, the first display configured to display an image in a first direction, and a second display having a second organic light emitting diode is on the second portion, the second display configured to display an image in a second direction. A gate driver is on the bending portion, and is configured to drive gate lines in each of the first and second displays.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.14/983,876, filed Dec. 30, 2015, which claims the benefit of the KoreanPatent Application No. 10-2015-0109144, filed on Jul. 31, 2015, bothwhich are hereby incorporated by reference for all purposes as if fullyset forth herein.

BACKGROUND Technical Field

The present invention relates to a flexible display device.

Discussion of the Related Art

Examples of a display device used for a monitor of a computer, a TV, acellular phone, etc., include an organic light emitting display (OLED),a plasma display panel (PDP), and a liquid crystal display (LCD). TheOLED and the PDP emit light by themselves, while the LCD needs aseparate light source.

Recently, a flexible display device fabricated of a flexible material,such as a plastic, has received attention as a next generation displaydevice, and may display an image even in the example that the device isflexible like paper.

Such a flexible display device has various applications, ranging frompersonal portable device to monitors of a computer, TVs, and more, and aflexible display device that has a reduced volume and a reduced weight,while keeping a wide display area, has been studied.

Mass production of flexible display devices has been recently applied tosmall mobile products, TVs, etc., while manufacturers of display devicescontinue to study development of a more advanced type of display deviceusing flexible properties.

SUMMARY

Accordingly, embodiments of the present invention are directed to aflexible display device and a method for fabricating the same, whichsubstantially obviate one or more problems due to limitations anddisadvantages of the related art.

An object of embodiments of the present invention is to provide a newtype of flexible display device based on a property of a flexiblesubstrate and a method for fabricating the same, and to provide astructure for reducing a bezel area where an image is not displayed anda method for fabricating the same.

To achieve these objects and other advantages and in accordance with thepurpose of embodiments of the invention, as embodied and broadlydescribed herein, a flexible display device comprises a flexiblesubstrate including first and second portions that overlap each other,and a bending portion connecting the first portion with the secondportion; a first display having a first organic light emitting diode onthe first portion, the first display configured to display an image in afirst direction; a second display having a second organic light emittingdiode on the second portion, the second display configured to display animage in a second direction; and a gate driver on the bending portion,the gate driver configured to drive gate lines in each of the first andsecond displays.

In another aspect, a method for fabricating a flexible display devicecomprises attaching a mother flexible substrate to a support substrate;forming a thin film transistor array on the mother flexible substrate todefine a plurality of unit areas; forming an organic light emittingdiode on the thin film transistor array; forming a unit flexiblesubstrate by cutting the support substrate and the mother flexiblesubstrate to include two unit areas adjacent to each other; connecting adriving circuit to each of the two unit areas; separating the supportsubstrate from the unit flexible substrate; and bending the unitflexible substrate based on a center line between the two unit areassuch that the two unit areas overlap with each other.

In another aspect, a flexible display device comprises a flexiblesubstrate including a bending portion concavely bent along a centerline, and first and second portions at opposite ends of the bendingportion; a first display having a first organic light emitting diode onthe first portion; and a second display having a second organic lightemitting diode on the second portion.

In another aspect, a method for fabricating a flexible display devicecomprises attaching a mother flexible substrate to a support substrate;forming a thin film transistor array on the mother flexible substrate todefine a plurality of unit areas; forming an organic light emittingdiode on the thin film transistor array; forming a unit flexiblesubstrate by cutting the support substrate and the mother flexiblesubstrate to include two unit areas adjacent to each other; connecting adriving circuit to each of the two unit areas; separating the supportsubstrate from the unit flexible substrate; and concavely bending theunit flexible substrate based on a center line between the two unitareas to allow one side of one of the two unit areas to be in contactwith one side of the other one of the two unit areas.

It is to be understood that both the foregoing general description andthe following detailed description of embodiments of the presentinvention are exemplary and explanatory and are intended to providefurther explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiments of the invention andtogether with the description serve to explain principles of theinvention. In the drawings:

FIG. 1 is a cross-sectional view illustrating a flexible display deviceaccording to the first example embodiment of the present invention;

FIG. 2 is a plane view illustrating an example state before a substrateis bent in fabricating a flexible display device as shown in FIG. 1;

FIGS. 3A and 3B are flow charts of a method for fabricating a flexibledisplay device according to the first example embodiment of the presentinvention;

FIG. 4 is a plane view illustrating a mother flexible substrate;

FIGS. 5A to 5H illustrate a method for fabricating a flexible displaydevice according to the first example embodiment of the presentinvention;

FIG. 6 is a plane view illustrating a flexible display device accordingto the second example embodiment of the present invention;

FIG. 7 is a cross-sectional view illustrating a flexible display deviceas shown in FIG. 6;

FIG. 8 illustrates a 100 inch TV to which embodiments of the presentinvention are applied;

FIGS. 9A and 9B are flow charts of a method for fabricating a flexibledisplay device according to the second example embodiment of the presentinvention;

FIGS. 10A to 10H illustrate a method for fabricating a flexible displaydevice according to the second example embodiment of the presentinvention; and

FIG. 11 is a cross-sectional view illustrating a variation of theflexible display device shown in FIG. 6.

DETAILED DESCRIPTION

Terms disclosed in this specification should be understood as follows.The term of a singular expression should be understood to include amultiple expression as well as the singular expression if there is nospecific definition in the context. The terms such as “the first” and“the second” are used only to differentiate one element from otherelements. Thus, a scope of claims is not limited by these terms. Also,it should be understood that the term such as “include” or “have” doesnot preclude existence or possibility of one or more features, numbers,steps, operations, elements, parts or their combinations. It should beunderstood that the term “at least one” includes all combinationsrelated with any one item. For example, “at least one among a firstelement, a second element and a third element” may include allcombinations of two or more elements selected from the first, second andthird elements as well as each element of the first, second and thirdelements. Also, if it is mentioned that a first element is positioned“on or above” a second element, it should be understood that the firstand second elements may be brought into contact with each other, or athird element may be interposed between the first and second elements.

Hereinafter, example embodiments of a flexible display device and amethod for fabricating the same according to the present invention willbe described with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view illustrating a flexible display deviceaccording to the first example embodiment of the present invention. FIG.2 is a plane view illustrating a state before a substrate is bent infabricating a flexible display device shown in FIG. 1.

With reference to FIG. 1, the flexible display device according to thefirst example embodiment includes a flexible substrate 100, first andsecond display units 200 and 300 arranged on the flexible substrate 100,and a driving circuit 400 connected to one side of the flexiblesubstrate 100.

The flexible substrate 100 has a bending property. To this end, plastic,which includes polyethylene naphthalate, polyethylene terephthalate,polycarbonate and polyethersulfone, and a metal foil, which includesStainless Steel (SUS), may be used as materials of the flexiblesubstrate 100.

One side of the flexible substrate 100 is bent. In more detail, as shownin FIG. 2, the flexible substrate 100 is bent based on its center lineCL. That is, the flexible substrate 100 according to the first exampleembodiment is formed such that that the first and second display units200 and 300 are formed on the flexible substrate 100, which is flat, andthen the flexible substrate 100 is bent.

Therefore, the flexible substrate 100 includes a first portion 110, asecond portion 120, and a bending portion 130, wherein the first portion110 and the second portion 120 overlap with each other when the flexiblesubstrate 100 is bent. The first portion 110 and the second portion 120have the same shapes and areas as each other. One side of the firstportion 110 is connected to one side of the second portion 120 by thebending portion 130.

In this example, the bending portion 130 of the flexible substrate 100is fixed with a specific curvature. To this end, a support member 500for supporting and fixing the flexible substrate 100 is disposed on thebending portion 130.

A cross-section of the support member 500 includes a flat surface and acurved surface convexedly extended from the flat surface to one side,and having a specific curvature. The curved surface of the supportmember 500 is arranged toward the center line CL of the flexiblesubstrate 100. In this example, the center line CL is disposed at thebending portion 130 of the flexible substrate 100.

The first display unit 200 is disposed on the first portion 110 of theflexible substrate 100. The first display unit 200 includes a firstorganic light emitting diode 220 displaying an image in a firstdirection.

In more detail, the first display unit 200 may include a thin filmtransistor array 210 disposed on the first portion 110 of the flexiblesubstrate 100, a first organic light emitting diode 220 deposited on thethin film transistor array 210, and an encapsulation layer 600 coveringthe first organic light emitting diode 220.

The first direction may be an upward direction of the flexible substrate100. Therefore, the first organic light emitting diode 220 displays animage in an upward direction of the flexible substrate 100.

The second display unit 300 is disposed on the second portion 120 of theflexible substrate 100. The second display unit 300 includes a secondorganic light emitting diode 320 displaying an image in a seconddirection.

In more detail, the second display unit 300 may include a thin filmtransistor array 310 disposed on the second portion 120 of the flexiblesubstrate 100, a second organic light emitting diode 320 deposited onthe thin film transistor array 310, and an encapsulation layer 600covering the second organic light emitting diode 320. In this example,the second organic light emitting diode 320 displays an image in asecond direction.

The second direction may be a downward direction of the flexiblesubstrate 100. Therefore, the second organic light emitting diode 320displays an image in a downward direction of the flexible substrate 100.

As described above, in the flexible display device according to thefirst example embodiment of the present invention, one side of theflexible substrate 100 is bent. The organic light emitting diodes 220and 320 are respectively arranged on the first portion 110 and thesecond portion 120 of the flexible substrate 100, which overlap eachother, whereby a dual display device displaying an image in dualdirections is realized.

In an example, the first and second organic light emitting diodes 220and 320 include a structure of an anode electrode, a hole injectionlayer, an organic light emitting layer, an electron injection layer, anda cathode electrode, deposited in due order.

Emission principles of the first and second organic light emittingdiodes 220 and 320 will briefly be described as follows. If electronsgenerated from the cathode electrode and holes generated from the anodeelectrode are injected into the light emitting layer, excitons aregenerated by a combination of the injected electrons and holes. Then,the excitons are transited from an excited state to a ground state toemit light, whereby an image is displayed.

As shown in FIG. 1, a polarizing film 700 for improving an ambientcontrast ratio (ACR) may be provided on the uppermost layers of thefirst and second display units 200 and 300.

The driving circuit 400 includes a first driving circuit 410 connectedto the first portion 110 of the flexible substrate 100 and a seconddriving circuit 420 connected to the second portion 120 of the flexiblesubstrate 100.

The first driving circuit 410 includes a printed circuit board 414provided at one side of the flexible substrate 100 and a plurality ofcircuit films 412 connecting the printed circuit board 414 with theflexible substrate 100.

The printed circuit board 414 is provided with a control circuit, whichis not shown, and a driving voltage generating circuit. In this example,the printed circuit board 414 may be a flexible printed circuit board(FPCB).

The plurality of circuit films 412 may be chip on films (COF), each ofwhich may be provided with a data drive integrated circuit (IC) 430packaged therein.

The printed circuit board 414 and the plurality of circuit films 412 arefolded with respect to a rear surface of the flexible substrate 100 andthen arranged between the first portion 110 and the second portion 120of the flexible substrate 100 as the flexible substrate 100 is bent.

The second driving circuit 420 includes elements substantially the sameas those of the first driving circuit 410. That is, the second drivingcircuit 420 includes a printed circuit board 424 provided at one side ofthe flexible substrate 100 and a plurality of circuit films 422connecting the printed circuit board 424 with the flexible substrate100.

Meanwhile, the first driving circuit 410 further includes a first gatedriver 230 for driving a plurality of gate lines provided in the firstdisplay unit 200. The first gate driver 230 is provided at one side ofthe first display unit 200.

Also, the second driving circuit 420 further includes a second gatedriver 240 for driving a plurality of gate lines provided in the seconddisplay unit 300. The second gate driver 240 is provided at one side ofthe second display unit 300.

The first and second gate drivers 230 and 240 are disposed between thefirst display unit 200 and the second display unit 300. Therefore, aplurality of gate signal transmission lines TL2 for transmitting aplurality of first and second gate control signals provided respectivelyfrom the first and second driving circuits 410 and 420 to each of thefirst and second gate drivers 230 and 240 are arranged between the firstdisplay unit 200 and the second display unit 300.

In the first example embodiment, the gate drivers and the gate signaltransmission lines TL2 for transmitting the plurality of gate controlsignals to the gate drivers are arranged in the bending portion 130.According to example embodiments of the present invention, the gatedrivers 230 and 240 and the plurality of gate signal transmission linesTL2 are not arranged in an outer bezel area of each of the first andsecond display units 200 and 300, whereby a width of the outer bezelarea may be reduced.

Meanwhile, in the first example embodiment, as the plurality of gatesignal transmission lines TL2 are arranged in the bending portion 130, astructure for the plurality of gate signals to be transferred from theprinted circuit board 414 to the flexible substrate 100 is varied. Thiswill be described in more detail as follows.

Generally, the circuit films 412 may package the data drive IC 430therein to drive the data lines arranged in the display unit. Some ofthe plurality of circuit films 412 transfer gate control signals and adriving voltage, provided from the printed circuit board 414, to theflexible substrate 100.

To this end, in the display device of the related art, a transfer lineTL1 for transferring gate control signals and a driving voltage providedform the printed circuit board 414 to the flexible substrate 100 may beprovided in the outermost circuit film 412 among the plurality ofcircuit films 412. This is because a gate driver is provided at one sideof the flexible substrate 100.

On the other hand, in the first example embodiment, because the gatedriver is arranged along the bending portion 130 of the flexiblesubstrate 100, that is, the center line CL, the transfer line TL1 isarranged in the circuit film 412 arranged at the center among theplurality of circuit films 412. For example, with reference to theexample shown in FIG. 2, if six circuit films 412 are provided, thetransfer line TL1 is arranged at the third and fourth circuit films 412.

Hereinafter, a method for fabricating the aforementioned flexibledisplay device according to the first example embodiment of the presentinvention will be described in detail.

FIGS. 3A and 3B are flow charts of a method for fabricating a flexibledisplay device according to the first example embodiment of the presentinvention. FIG. 4 is a plane view illustrating a mother flexiblesubstrate MS. FIGS. 5A to 5H illustrate a method for fabricating aflexible display device according to the first example embodiment of thepresent invention.

With reference to FIGS. 3A and 3B, the method for fabricating theflexible display device according to the first example embodimentincludes a step (first process) S10 of attaching the mother flexiblesubstrate MS to the support substrate 1000, a step (second process) S20of forming the thin film transistor array 210 on the mother flexiblesubstrate MS, a step (third process) S30 of forming an organic lightemitting diode on the thin film transistor array 210, a step (fourthprocess) S40 of cutting the mother flexible substrate MS, a module step(fifth process) S50 of connecting the driving circuit 400 to a unit areaUA formed by cutting of the mother flexible substrate MS, a step (sixthprocess) S60 of separating the support substrate 1000 from the motherflexible substrate MS, and a step (sixth process) S70 of attaching thepolarizing film 700 to each unit area UA.

In the first example embodiment, the method further includes a step(eighth process) S80 of bending the mother flexible substrate MS aftercutting the mother flexible substrate MS. The eighth process S80 may beperformed before or after the step of attaching the polarizing film 700to each unit area UA.

With reference to FIG. 5A, the first process S10 is to attach the motherflexible substrate MS to the support substrate 1000 to facilitatehandling of the mother flexible substrate MS during the processes. Thesupport substrate 1000 is attached to the rear surface of the flexiblesubstrate 100 such that the mother flexible substrate MS is neithereasily bent nor distorted during a later process. To this end, a glasssubstrate thicker than the mother flexible substrate MS may be used asthe support substrate 1000.

The mother flexible substrate MS is divided into a plurality of unitareas UA. Each of the plurality of unit areas UA corresponds to a singleunit display device. In the drawing, one mother flexible substrate MS isconfigured to generate six unit display devices. However, the number ofunit display devices that may be generated by one mother flexiblesubstrate MS is not limited to the examples shown and described herein.

With reference to FIG. 5B, the second process S20 is to form the thinfilm transistor array 210 after the first process S10. The thin filmtransistor array 210 is formed per the plurality of unit areas UA. Thethin film transistor array 210 includes gate lines, data lines crossingthe gate lines, a plurality of signal transmission lines, a plurality ofpad electrodes, and a thin film transistor connected to the gate anddata lines.

The second process S20 includes the step of forming a gate driver and aplurality of gate signal lines TL2 connected to the gate driver betweenneighboring unit areas UA adjacent to each other. In this example, thegate driver includes first and second gate drivers 230 and 240 arrangedto be adjacent to each other. The first gate driver 230 is connected tothe first unit area UA of the neighboring unit areas, which is arrangedat one side, and the second gate driver 240 is connected to the secondunit area UA of the neighboring unit areas, which is arranged at theother side.

With reference to FIG. 5C, the third process S30 is to form the organiclight emitting diode after the second process S20. The organic lightemitting diode is formed for each of the plurality of unit areas UA. Theorganic light emitting diode is divided into the first light emittingdevice 220 and the second light emitting device 320 during a laterprocess. In more detail, in the later fourth process S40, the motherflexible substrate MS is cut on a basis of two unit areas UA, wherebythe organic light emitting diode is divided into the first organic lightemitting diode 220 and the second organic light emitting diode 320,which are arranged respectively in two unit areas UA.

With reference to FIG. 5D, the fourth process S40 is to cut the motherflexible substrate MS on a basis of two unit areas UA after the thirdprocess S30. In more detail, the fourth process S40 is to cut the motherflexible substrate MS on a basis of the outside of the unit area UA, inaccordance with the intended use of the display, and/or designspecifications. The method for fabricating the flexible display deviceaccording to the first example embodiment may facilitate realization ofa dual display device by cutting two unit areas UA at a time, andthereby improve process throughput.

Hereinafter, for convenience of description, each mother flexiblesubstrate MS separated by cutting two unit areas UA during the fourthprocess S40 will be termed a “unit flexible substrate US.” For example,in FIG. 4, one mother flexible substrate MS is configured to generatesix unit display devices. In this example, the one mother flexiblesubstrate MS is cut to generate three unit flexible substrates US. Forreference, the flexible substrate 100 shown in FIGS. 1 and 2 representsone unit flexible substrate US.

With reference to FIG. 5E, the fifth process S50 is to connect thedriving circuit 400 after the fourth process S40. In more detail, thefifth process S50 is to connect the driving circuit 400 to a pluralityof pads formed on the unit flexible substrate US during the secondprocess S20. At this time, the circuit films 412 of the driving circuit400 are connected to the plurality of pads in a type of tape automatedbonding (TAB). Therefore, each unit area UA is connected to the printedcircuit board 414 through the circuit films 412.

With reference to FIG. 5F, the sixth process S60 is to separate thesupport substrate 1000 from the unit flexible substrate US. The unitflexible substrate US has flexibility after the sixth process S60.

With reference to FIG. 5G, the seventh process S70 is to attach thepolarizing film 700 to each unit area UA. The polarizing film 700 isattached to an encapsulation substrate 600, which encapsulates the firstand second organic light emitting diodes 220 and 320, and serves toimprove an ambient contrast ratio (ACR).

With reference to FIG. 5H, the eighth process S80 is to bend the unitflexible substrate US. In more detail, the eighth process S80 is tosuperimpose two unit areas UA on each other by bending the unit flexiblesubstrate US based on the center line CL arranged between the two unitareas UA. In this eighth process S80, the printed circuit board 414 andthe plurality of circuit films 412 are folded toward the rear surface ofthe flexible substrate 100. That is, the printed circuit board 414 andthe plurality of circuit films 412 are arranged between the firstportion 110 and the second portion 120 of the unit flexible substrate USas the unit flexible substrate US is bent.

FIG. 6 is a plane view illustrating a flexible display device accordingto a second example embodiment of the present invention. FIG. 7 is across-sectional view illustrating a flexible display device shown inFIG. 6. FIG. 8 illustrates a 100 inch TV to which embodiments of thepresent invention are applied.

With reference to FIG. 6, the flexible display device according to thesecond example embodiment includes a flexible substrate 100, first andsecond display units 200 and 300 disposed on the flexible substrate 100,and a driving circuit 400 connected to one side of the flexiblesubstrate 100.

The flexible substrate 100 has a bending property. To this end, plastic,which includes polyethylene naphthalate, polyethylene terephthalate,polycarbonate and polyethersulfone, and a metal foil, which includesstainless steel (SUS), may be used as materials of the flexiblesubstrate 100.

A center area of the flexible substrate 100 is bent. In more detail, asshown in FIG. 6, the flexible substrate 100 has a bending portion 130concavely bent based on its center line CL.

Therefore, the flexible substrate 100 includes a first portion 110, asecond portion 120, and a bending portion 130 arranged between the firstand second portions 110 and 120, wherein the first portion 110 and thesecond portion 120 have the same height as each other. That is, thebending portion 130 is formed along the center line CL, and the firstand second portions 110 and 120 are arranged at both sides of thebending portion 130. The first and second portions 110 and 120 may havethe same shape and the same area as each other.

In the second example embodiment, as the bending portion 130 is formedalong the center line CL, an interval between the display units providedin each of the first and second portions 110 and 120 may be reduced.

In this example, the bending portion 130 of the flexible substrate 100is fixed with a specific curvature. To this end, a support member 500for supporting and fixing the flexible substrate 100 is disposed on thebending portion 130.

A cross-section of the support member 500 includes a flat surface havingthe same height as those of the first and second portions 110 and 120and a curved surface concavely extended from the flat surface to a lowerside, and having a specific curvature. The curved surface of the supportmember 500 is arranged toward a rear surface of the flexible substrate100.

The first display unit 200 is disposed on the first portion 110 of theflexible substrate 100. In more detail, the first display unit 200 mayinclude a thin film transistor array 210 disposed on the first portion110 of the flexible substrate 100, a first organic light emitting diode220 deposited on the thin film transistor array 210, and anencapsulation layer 600 covering the first organic light emitting diode220.

The second display unit 300 is disposed on the second portion 120 of theflexible substrate 100. In more detail, the second display unit 300 mayinclude a thin film transistor array 310 disposed on the second portion120 of the flexible substrate 100, a second organic light emitting diode320 deposited on the thin film transistor array 310, and anencapsulation layer 600 covering the second organic light emitting diode320.

As described above, in the flexible display device according to thesecond example embodiment of the present invention, the center area ofthe flexible substrate 100 is bent concavely. In example embodiments ofthe present invention as above, the first and second display units 200and 300, which may be driven independently from each other, areconnected with each other, whereby a multi-vision display device may berealized. A width of a non-display area disposed between the first andsecond display units 200 and 300 is reduced by the bending portion 130,whereby a seam area between the first and second display units 200 and300 may be realized to be close to or about zero.

Therefore, in embodiments of the present invention, two independent unitdisplay devices may be connected to each other, and at the same time, azero or about zero seam may be realized, whereby a large scale displaydevice may easily be realized. For example, 100 inch TVs, asmass-produced by manufacturers of display devices, have been expensiveproducts up to now, but their manufacture may be facilitated and theirmanufacturing cost may be reduced if two 55 inch display panels areconnected to each other, as shown in FIG. 8 and in accordance withembodiments of the present invention.

According to embodiments of the present invention, because the first andsecond display units 200 and 300, which are independent from each other,are connected to each other, a large scale TV may be realized. For thisreason, 120 Hz driving, which may be difficult to realize inconventional 100 inch-TVs due to RC delay, may be more easily realized.Images of higher quality may therefore be provided.

For reference, the 120 Hz driving technique may provide images of highquality by providing images of 120 frames per 1 second. The 120 Hzdriving technique may be applied to a 55 inch display device. However,due to RC delay in the signal lines, it has been difficult to realizethe 120 Hz driving technique in a large scale display screen. For thisreason, the 120 Hz driving technique has typically not been applied todisplay devices of more than 55 inches.

With reference to the first and second organic light emitting diodes 220and 320 of the second example embodiment, these diodes include astructure of an anode electrode, a hole injection layer, an organiclight emitting layer, an electron injection layer, and a cathodeelectrode, deposited in due order.

Emission principles of the first and second organic light emittingdiodes 220 and 320 are similar to those of the first example embodiment,but will briefly be described as follows. If electrons generated fromthe cathode electrode and holes generated from the anode electrode areinjected into the light emitting layer, excitons are generated bycombination of the injected electrons and holes. Then, the excitons aretransited from an excited state to a ground state to emit light, wherebyan image is displayed.

As shown in FIG. 7, a polarizing film 700 for improving an ambientcontrast ratio (ACR) may be provided on the uppermost layers of thefirst and second display units 200 and 300.

The driving circuit 400 includes a first driving circuit 410 connectedto the first portion 110 of the flexible substrate 100 and a seconddriving circuit 420 connected to the second portion 120 of the flexiblesubstrate 100.

The first driving circuit 410 includes a printed circuit board 414provided at one side of the flexible substrate 100, and a plurality ofcircuit films 412 connecting the printed circuit board 414 with theflexible substrate 100.

The printed circuit board 414 is provided with a control circuit, whichis not shown, and a driving voltage generating circuit. In this example,the printed circuit board 414 may be a flexible printed circuit board(FPCB).

The plurality of circuit films 412 may be chip on films (COF), each ofwhich may be packaged with a data drive integrated circuit (IC) 430therein.

The second driving circuit 420 includes elements substantially the sameas those of the first driving circuit 410. That is, the second drivingcircuit 420 includes a printed circuit board 424 provided at one side ofthe flexible substrate 100, and a plurality of circuit films 422connecting the printed circuit board 424 with the flexible substrate100.

Meanwhile, the first driving circuit 410 further includes a first gatedriver 230 for driving a plurality of gate lines provided in the firstdisplay unit 200. The first gate driver 230 is provided at one side ofthe first display unit 200. Also, the second driving circuit 420 furtherincludes a second gate driver 240 for driving a plurality of gate linesprovided in the second display unit 300. The second gate driver 240 isprovided at one side of the second display unit 300.

The first and second gate drivers 230 and 240 are disposed between thefirst display unit 200 and the second display unit 300. Therefore, aplurality of gate signal transmission lines TL2 for transmitting aplurality of first and second gate control signals provided from thefirst and second driving circuits 410 and 420 to each of the first andsecond gate drivers 230 and 240 are arranged between the first displayunit 200 and the second display unit 300.

In the second example embodiment, the gate drivers and the gate signaltransmission lines TL2 for transmitting the plurality of gate controlsignals to the gate drivers are arranged in the bending portion 130.According to example embodiments of the present invention, the gatedrivers 230 and 240 and the plurality of gate signal transmission linesTL2 are not arranged in an outer bezel area of each of the first andsecond display units 200 and 300, whereby a width of the outer bezelarea may be reduced.

Hereinafter, a method for fabricating the aforementioned flexibledisplay device according to the second example embodiment of the presentinvention will be described in detail.

FIGS. 9A and 9B are flow charts of a method for fabricating a flexibledisplay device according to the second example embodiment of the presentinvention. FIGS. 10A to 10H illustrate a method for fabricating aflexible display device according to the second example embodiment ofthe present invention.

With reference to FIGS. 9A and 9B, a method for fabricating the flexibledisplay device according to the second example embodiment includes astep (first process) S10 of attaching a mother flexible substrate MS toa support substrate 1000, a step (second process) S20 of forming thethin film transistor array 210 on the mother flexible substrate MS, astep (third process) S30 of forming an organic light emitting diode onthe thin film transistor array 210, a step (fourth process) S40 ofcutting the mother flexible substrate MS, a module step (fifth process)S50 of connecting the driving circuit 400 to a unit area UA formed bycutting of the mother flexible substrate MS, a step (sixth process) S60of separating the support substrate 1000 from the mother flexiblesubstrate MS, and a step (sixth process) S70 of attaching the polarizingfilm 700 to each unit area UA.

In the second example embodiment, the method further includes a step(eighth process) S80 of bending the mother flexible substrate MS aftercutting the mother flexible substrate MS. The eighth process S80 may beperformed before or after the step of attaching the polarizing film 700to each unit area UA.

With reference to FIG. 10A, the first process S10 is to attach themother flexible substrate MS to the support substrate 1000 to facilitatehandling of the mother flexible substrate MS during the processes. Thesupport substrate 1000 is attached to the rear surface of the flexiblesubstrate 100 such that the mother flexible substrate MS is neither bentnor distorted during a later process. To this end, a glass substratethicker than the mother flexible substrate MS may be used as the supportsubstrate 1000.

The mother flexible substrate MS is divided into a plurality of unitareas UA. Each of the plurality of unit areas UA corresponds to a singleunit display device.

With reference to FIG. 10B, the second process S20 is to form the thinfilm transistor array 210 after the first process S10. The thin filmtransistor array 210 is formed per the plurality of unit areas UA. Thethin film transistor array 210 includes gate lines, data lines crossingthe gate lines, a plurality of signal transmission lines, a plurality ofpad electrodes, and a thin film transistor connected to the gate anddata lines.

The second process S20 includes the step of forming a gate driver and aplurality of gate signal lines TL2, which are connected to the gatedriver, between neighboring unit areas UA adjacent to each other. Inthis example, the gate driver includes first and second gate drivers 230and 240 arranged to be adjacent to each other. The first gate driver 230is connected to the first unit area UA of the neighboring unit areas,which is arranged at one side, and the second gate driver 240 isconnected to the second unit area UA of the neighboring unit areas,which is arranged at the other side.

With reference to FIG. 10C, the third process S30 is to form the organiclight emitting diode after the second process S20. The organic lightemitting diode is formed for each of the plurality of unit areas UA. Theorganic light emitting diode is divided into the first light emittingdevice 220 and the second light emitting device 320 during a laterprocess. In more detail, in the later fourth process S40, the motherflexible substrate MS is cut on a basis of two unit areas UA, wherebythe organic light emitting diode is divided into the first organic lightemitting diode 220 and the second organic light emitting diode 320,which are arranged respectively in two unit areas UA.

With reference to FIG. 10D, the fourth process S40 is to cut the motherflexible substrate MS on a basis of two unit areas UA after the thirdprocess S30. In more detail, the fourth process S40 is to cut the motherflexible substrate MS on a basis of the outside of the unit area UA inaccordance with the intended use of the display and/or designspecifications. The method for fabricating the flexible display deviceaccording to the second example embodiment may facilitate realization ofa multi-vision display device by cutting two unit areas UA at a time,and thereby improve process throughput.

Hereinafter, for convenience of description, each mother flexiblesubstrate MS separated by cutting two unit areas UA during the fourthprocess S40 will be termed a “unit flexible substrate US”.

With reference to FIG. 10E, the fifth process S50 is to connect thedriving circuit 400 after the fourth process S40. In more detail, thefifth process S50 is to connect the driving circuit 400 to a pluralityof pads formed on the unit flexible substrate US during the secondprocess S20. At this time, the circuit films 412 of the driving circuit400 are connected to the plurality of pads in a type of tape automatedbonding (TAB). Therefore, each unit area UA is connected to the printedcircuit board 414 through the circuit films 412.

With reference to FIG. 10F, the sixth process S60 is to separate thesupport substrate 1000 from the unit flexible substrate US. The unitflexible substrate US has flexibility by means of the sixth process S60.

With reference to FIG. 10G, the seventh process S70 is to attach thepolarizing film 700 to each unit area UA. The polarizing film 700 isattached to an encapsulation substrate 600, which encapsulates the firstand second organic light emitting diodes 220 and 320, and serves toimprove an ambient contrast ratio (ACR).

With reference to FIG. 10H, the eighth process S80 is to bend the unitflexible substrate US. In more detail, the eighth process S80 is toconcavely bend the center area of the flexible substrate 100 based onthe center line CL arranged between the two unit areas UA. In thiseighth process S80, the printed circuit board 414 and the plurality ofcircuit films 412 are folded toward the rear surface of the flexiblesubstrate 100.

Meanwhile, the eighth process S80 may use the support member 500 to bendthe unit flexible substrate US. In more detail, the eighth process S80may include the steps of arranging the support member 500 to correspondto the center line CL of the unit flexible substrate US, and concavelybending a part of the unit flexible substrate US while surrounding asurface of the support member 500.

In this example, a cross-section of the support member 500 includes aflat surface and a curved surface concavely extended from the flatsurface to one side, and having a specific curvature. Therefore, onesides of the two unit areas UA are in contact with each other byinterposing the flat surface of the support member 500 therebetween.

FIG. 11 illustrates a variation of the second example embodiment. InFIG. 11, the polarizing film 700 is disposed across both of the unitareas UA1 and UA2, including above the support member 500. In this way,a seam between the unit areas UA1 and U2 may be less noticeable.

As described above, in the flexible display device according toembodiments of the present invention, one side of the flexible substrate100 is bent, and the organic light emitting diodes 220 and 320 arerespectively arranged above the first portion 110 and the second portion120 of the flexible substrate 100, which are superimposed on each other,whereby a dual display device displaying an image in a dual direction isrealized. According to embodiments of the present invention, the gatedrivers and the gate signal transmission lines TL2 for transmitting theplurality of gate control signals to the gate drivers are arranged inthe bending portion 130 between the first and second portions 110 and120, whereby the width of the outer bezel area may be reduced.

Also, the method for fabricating the flexible display device accordingto embodiments of the present invention may facilitate realization ofthe dual display device by cutting two unit areas UA at a time, andthereby improve process throughput.

Also, in the flexible display device according to embodiments of thepresent invention, the first and second display units 200 and 300, whichmay be driven independently from each other, are connected with eachother, whereby the multi-vision display device may be provided. As thebending portion arranged 130 between the first and second display units200 and 300 is bent concavely, the width of the non-display area may bereduced, and the seam area between the first and second display units200 and 300 may be realized to be close to or about zero. Therefore, inembodiments of the present invention, a large scale TV, such as a 100inch-TV, may easily be fabricated, and its fabricating cost may bereduced.

Also, in embodiments of the present invention, because the first andsecond display units 200 and 300, which are independent from each other,may be connected to each other, a large scale TV may be realized.Therefore, 120 Hz driving, which is difficult to realize in theconventional large-scale display device due to RC delay, may herein berealized more easily, whereby images of high quality may be provided.

Also, methods for fabricating the flexible display device according toexample embodiments of the present invention may facilitate realizationof the multi-vision display device by cutting two unit areas UA at atime, and thereby improve process throughput.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A flexible display device, comprising: a flexiblesubstrate including: first and second portions that overlap each other,and a bending portion connecting the first portion with the secondportion; a first display having a first organic light emitting diode onthe first portion; a second display having a second organic lightemitting diode on the second portion; a first gate driver on the bendingportion, the first gate driver configured to drive gate lines in thefirst display; and a second gate driver on the bending portion, thesecond gate driver configured to drive gate lines in the second display,wherein the first gate driver and the second gate driver are provided inthe bending portion between the first display and the second display,and are connected to a first and second driving circuit respectively. 2.The flexible display device of claim 1, wherein the flexible substrateis bent based on a center line in the bending portion.
 3. The flexibledisplay device of claim 2, wherein the center line in the bendingportion is provided between the first gate driver and the second gatedriver.
 4. The flexible display device of claim 2, wherein the firstgate driver and the second gate driver are provided along with thecenter line in the bending portion.
 5. The flexible display device ofclaim 1, wherein the flexible substrate has a first and second side, thefirst and second portions are provided along with the first side, thebending portion is provided along with the second side, and the firstside is longer than the second side in the flexible substrate.
 6. Theflexible display device of claim 1, wherein the first and secondportions have the same shape and area as each other.
 7. The flexibledisplay device of claim 1, wherein the first driving circuit isconnected to one side of the first portion, the first driving circuit isconfigured to supply a plurality of first driving signals to the firstdisplay and the first gate driver, the second driving circuit isconnected to one side of the second portion, and the second drivingcircuit is configured to supply a plurality of second driving signals tothe second display and the second gate driver.
 8. The flexible displaydevice of claim 7, wherein a gap between the first driving circuit andthe second driving circuit facing the first driving circuit is smallerthan a gap between the first display and the second display.
 9. Theflexible display device of claim 7, wherein a plurality of gate signaltransmission lines for transmitting a plurality of gate control signalsfrom the first and second driving circuits to the gate drivers are inthe bending portion.
 10. The flexible display device of claim 7, whereinthe first driving circuit includes a printed circuit board and aplurality of circuit films, and the second driving circuit includes aprinted circuit board and a plurality of circuit films.
 11. The flexibledisplay device of claim 10, wherein a plurality of gate signaltransmission lines for transmitting a plurality of gate control signalsfrom the printed circuit board of the first driving circuit to the firstgate driver is provided on one of the plurality of circuit films of thefirst driving circuit, a plurality of gate signal transmission lines fortransmitting a plurality of gate control signals from the printedcircuit board of the second driving circuit to the second gate driver isprovided on one of the plurality of circuit films of the second drivingcircuit, and the one of the plurality of circuit film of the firstdriving circuit and the one of the plurality of circuit film of thesecond driving circuit are respectively provided in a region adjacent toa center line in the bending portion.
 12. The flexible display device ofclaim 11, wherein each of the plurality of gate signal transmissionlines has at least one curved portion.
 13. The flexible display deviceof claim 12, wherein the plurality of gate signal transmission linesprovided on the first portion and the plurality of gate signaltransmission lines provided on the second portion are formed to besymmetric with respect to the center line.
 14. The flexible displaydevice of claim 1, wherein a size of the first display and a size of thesecond display is same or different.
 15. The flexible display device ofclaim 1, wherein the first display includes: a thin film transistorarray disposed on the first portion; a first organic light emittingdiode deposited on the thin film transistor array; and and anencapsulation layer covering the first organic light emitting diode, andthe second display includes: a thin film transistor array disposed onthe second portion; a second organic light emitting diode deposited onthe thin film transistor array; and an encapsulation layer covering thesecond organic light emitting diode.
 16. The flexible display device ofclaim 15, wherein the encapsulation layer of the first display coversthe first gate driver, and the encapsulation layer of the second displaycovers the second gate driver.
 17. The flexible display device of claim15, wherein a polarizing film is provided on at least one of theencapsulation layers of the first and second displays.
 18. The flexibledisplay device of claim 7, wherein the first display and the seconddisplay are provided on a first surface of the flexible substrate, thefirst driving circuit and the second driving circuit are provided on asecond surface of the flexible substrate, the first surface and thesecond surface being opposite to each other, and when the first portionand the second portion overlaps each other, the first driving circuitand the second driving circuit are provided to face each other.
 19. Theflexible display device of claim 7, wherein the first gate driver andthe second gate driver is provided on a first surface of the flexiblesubstrate, the first driving circuit and the second driving circuit areprovided on a second surface of the flexible substrate, and the firstsurface and the second surface are opposite to each other.
 20. Theflexible display device of claim 10, wherein one of the plurality ofcircuit film of the first driving circuit connected to a plurality ofgate signal transmission lines is provided in a region adjacent to acenter line in the bending portion, and one of the plurality of circuitfilm of the second driving circuit connected to a plurality of gatesignal transmission lines is provided in a region adjacent to a centerline in the bending portion.